5155-50-0Relevant academic research and scientific papers
Regioselective methylation of methyl glycopyranosides with diazomethane in the presence of transition-metal chlorides and of boric acid
Evtushenko, Evgeny V.
, p. 187 - 200 (2007/10/03)
Partial methylation of the methyl pyranosides of a number of pentoses, hexoses, 6-deoxyhexoses, methyl uronates and their methyl ethers with diazomethane in the presence of transition-metal chlorides and boric acid was studied. It was found for methyl glycosides of pentoses and 6-deoxyhexoses that tin(II), antimony(III), and titanium(IV) chlorides as well as boric acid promoted substitution mainly of OH-3, but with cerium(III) and zinc(II) salts mainly substitution of OH-2 was observed. Methylation of methyl β-l-rhamnopyranoside demonstrated higher reactivity of OH-2 in all cases. The methylation of methyl glycosides of hexoses in the presence of tin(II), antimony(III) and cerium(III) chlorides gave mainly 3-methyl ethers. The 3-methyl ethers, which are not involved in further complexation, accumulated up to 50-80% of the reaction mixture (95-100% of monomethyl ether fraction). Convenient preparative syntheses of methyl ethers for a number of sugars are suggested. Copyright (C) 1999 Elsevier Science Ltd.
Regioselective Monoalkylation of Non-protected Glycopyranosides by the Dibutyltin Oxide Method
Haque, Mohammed Ekramul,Kikuchi, Tohru,Yoshimoto, Kimihiro,Tsuda, Yoshisuke
, p. 2243 - 2255 (2007/10/02)
Regioselective monoalkylation of some pento- and hexopyranosides (Me β-L-Ara, Ph α-L-Ara, Me α-D-Xyl, Me β-D-Xyl, Me α-D-Glc, Me β-D-Glc, Me α-D-Gal, Me β-D-Gal, and Me α-D-Man) was examined by using the dibutyltin oxide method without protecting the hydroxyl groups.By this method, alkylation proceeds more or less in the same fashion as reported for acylation (through the formation of cyclic tin intermediates) and selectively activates an equatorial hydroxyl group which has an oxygenated function (OH or OMe) in a cis relationship at an adjacent position, even in the presence of a more reactive primary hydroxyl group.However, in some instances the position of activation is different.Various monoalkyl ethers thus prepared were identified by analyses of their carbon-13 nuclear magnetic resonance spectra.Keywords-regioselective monoalkylation; glycopyranoside; dibutyltin oxide; cis-vicinal glycol; benzylation; allylation; methoxymethylation; methylation;13C-NMR
A Study of the Rapid Anomerization of Poly-O-benzyl-β-D-glucopyranosides with Titanium Tetrachloride
Koto, Shinkiti,Morishima, Naohiko,Kawahara, Reiko,Ishikawa, Katsuhiko,Zen, Shonosuke
, p. 1092 - 1096 (2007/10/02)
Titanium tetrachloride rapidly anomerizes methyl 2,3,4,6-tetra-O-benzyl-β-D-glucopyranoside in dichloromethane at 25 deg C.Evidence for the proposal that the benzyloxymethyl group on C-5 and the ring oxygen of the glucoside cooperate to prompt the reaction is described.The reagent anomerizes the interglycosidic linkage of several disaccharide derivatives.
